Altering the shape and the color of hair represents an important field of modern cosmetics. This allows the appearance of the hair to be adapted both to current fashion trends and to the individual desires of the particular consumer. The color design of hair styles in keeping with fashion or covering of graying or white hair with trendy or natural hues is usually carried out using color-altering agents. In addition to a high coloring performance, these agents are to have additional properties, such as to increase the hair volume.
Various dyeing systems are known in the prior art for providing color-altering cosmetic agents, in particular for the skin or for keratin-containing fibers, such as human hair.
Oxidation dyes are used for permanent, intensive colorations having appropriate fastness properties. Such dyes typically include oxidation dye precursors, referred to as developer components and coupler components. Under the influence of oxidizing agents or atmospheric oxygen, the developer components develop the actual dyestuffs among each other or by coupling to one or more coupler components. The oxidation dyes are characterized by outstanding, long lasting coloring results. For naturally appearing colorations, however, usually a mixture of a larger number of oxidation dye precursors are used; in many instances, direct dyes continue to be used for nuancing.
Permanent or semi-permanent coloring agents including what are known as direct dyes as the coloring component are typically used for temporary colorations. These are dye molecules that attach directly to the substrate and require no oxidative process to develop the color. Henna, which is already known for coloring the body and hair from ancient times, belongs to these dyes, for example. In general, these colorations are considerably more sensitive to shampooing than oxidative colorations, so that in many instances an undesirable shift in the nuance, or a visible homogeneous loss of color, takes place much earlier.
Finally, another dyeing method has attracted great interest. In this method, precursors of the natural hair pigment melanin are applied to the substrate, such as the hair; these precursors then develop nature-analogous dyes as part of oxidative processes in the hair. Such methods use 5,6-dihydroxyindoline as the dye precursor, for example. In particular, when using agents comprising 5,6-dihydroxyindoline multiple times, it is possible to restore the natural hair color of people having grayed hair. The dyeing result may be achieved using atmospheric oxygen as the only oxidizing agent, whereby additional oxidizing agents can be dispensed with. In people having originally ash blond to brown hair, 5.6-dihydroxyindoline may be used as the sole dye precursor. In contrast, satisfactory results in the use on people having originally a red, and in particular a dark to black, hair color, can frequently only be achieved by simultaneously using additional dye components, and more particularly special oxidation dye precursors.
The dyes known from the prior art, however, do not always result in the desired high coloring performance or do not have any adequate additional desirable properties, such as improved nourishment of the hair during dyeing of the hair.